The bonus is a one-off per data centre though remember....

Bonuses for characters created during bonus period that attain level 30 in any class
Gift of 1,000,000 gil (*1)
Gift of 15 days of free play time (*2)
*1 Limited to once per data center region on a single service account.
*2 Limited to once per service account when creating a new character on either a New World or Preferred World.